Corrosion inhibitor containing alkanoyloxyacetic acid and method of using same



EORROSION INHIBITQR CGNTAINWG ALKA- NOYLOXYACETIC ACID AND R'ETHGD OFUSING SAME Lester W. Kalinowski, Chicago, 111., assignor to Sinclair 8Claims. (Cl. 2.1-2.5)

My invention relates to corrosion inhibition and more particularly tovapor phase corrosion inhibition in which the inhibiting agent vaporizesto deposit a protective coating on metals.

In the transportation and storage of metals and metal products such assheet steel and machine parts in the channels of manufacture andcommerce, the metal objects are usually subject to the corrosive actionof water vapor. In order to prevent corrosion of metal objectsit hasbeen customary to wrap and seal them in moisture-proof wrappers orpackages, and in some instances, three or four layers ofmoisture-resistant wrapping have been used. However such precautionshave not been wholly successful for despite the best efforts corrosionstill takes place since some water vapor is usually trapped in thewrapping or packaging when it is sealed, and additional moisturepenetrates the interior of the wrapping or packaging after it is sealed.

These and other problems are overcome according to my invention bysurrounding the metal objects to be protected with an atmospherecontaining a vaporized alkanoyloxyacetic acid having from eight totwelve'carbon atoms in the alkanoyl group such as octanoyloxyaceticacid, decanoyloxyacetic acid and lauroyloxyacetic acid. The corrosioninhibiting vaporized acid deposits as a protective film on the metalobjects, making absolute sealing of the metal objects in moisture-proofwrappings or packaging unnecessary, and negating the corrosive efiect onthe metal objects of the moisture trapped in the wrapping or packagingwhen it is sealed.

In one aspect of my invention an atmosphere containing the corrosioninhibiting vaporized acid, advantageously lauroyloxyacetic acid, isformed by vaporization of the carbon vehicle must be non-volatile,inert, capable of forming a dispersion with the alkanoyloxyacetic acid,and capable of being applied to a packaging material. For example, thevehicle may be a virgin gas oil, a'heavy lube fraction, e. g. aconventionally prepared neutral of about 80 SSU at 212 F. or a brightstock, a paraflin or a microcrystalline wax, an asphalt or a bituminousproduct. The alkanoyloxyacetic acid may be of the type commerciallyavailable and its effective proportion is in the range of about 3% toabout 10% by weight based on the total composition. The wrapping orpackaging material may be fibrous materialsuch as paper, cardboard,textile, wood, fibreboard, etc., or it may be a non-fibrous materialsuch as cellophane, plastic compositions, etc. The inhibitorhydrocarboncomposition is applied as a coating to the wrapping or packagingmaterial by any suitable means.

In another aspect of my invention an atmosphere containing the corrosioninhibiting vaporized acid is formed by vaporization of thealkanoyloxyacetic acid in a closed nited States Patent 0 container. Thusthe alkanoyloxyacetic acid may be distributed directly within thecontainer in solid state in the form of dust or larger particles,indirectly enclosed in porous bags, etc. or it may be distributed in theliquid state in the form of molten acid or dissolved in a volatilesolvent. Here again the alkanoyloxyacetic acid may be of the typecommercially available and it should be distributed within the closedcontainer in amounts such that at least 0.01 pound of inhibitor arepresent for each cubic feet of air space.

The actual amount of inhibitor employed is ordinarily directly relatedto the amount of sealing of the wrapping or packaging material, the typeof metal to be protected, the degree of exposure to which the packagedmetal will be subjected, and the period of time during which it is to beprotected. In particular, enclosed or open air transportation or storagewith constantly varying temperature and humidity are capable ofaffecting corrosion considerably. However, if a coating compositioncontaining the alkanoyloxyacetic acid is applied to a packaging materialcarrier, the alkanoyloxyacetic acid should in general be present inamounts of about 2 grams per square foot of treated carrier. From aneconomic viewpoint, it is generally unnecessary to use more than about10% byweight of alkanoyloxyacetic acid in the coating composition.

Other closely related members of the same homologous series do notappear to have the special advantages of the alkanoyloxyacetic acidshaving between eight and twelve carbon atoms in the alkanoyl group. Forinstance, hex anoyloxyacetic acid and myristoyloxyacetic acid, eachremoved by only two carbon atoms from the acids in the above seriesevidence extremely poor vapor phase corrosion inhibiting capacity, as isdemonstrated by the tests described in Example I (infra).

Among the advantages of my coating compositions, are that I may coat apackaging material on one side only with a composition consisting ofmicrocrystalline wax (which penetrates the fibrous material to a limitedextent) and an alkanoyloxyacetic acid so that the inhibiting agentvaporizes from only one side of the packaging material and none is lostby penetration of the inhibiting vapor through the fibrous material intothe outside air. I thus dispense with the need for laminating thepackaging material to keep the inhibiting vapor in the enclosed spacecontaining the metal objects. Or I may impregnate the packaging materialwith a composition consisting of a heavy lube oil or a paraffin wax(which completely penetrate the fibrous material) and analkanoyloxyacetic acid so that the inhibiting agent vaporizes from bothsides of the packaging material, such material being useful to separate,for example, steel plates shipped or stored in layers.

The following examples are offered to illustrate more clearly the natureand effectiveness of certain alkanoyloxyacetic acids alone orincorporated in coating compositions as vapor phase rust inhibitorsaccording to my invention. However, it should be noted that the testsdescribed in the examples were conducted under extreme conditions oftemperature and humidity. In commercial use of my inhibitor theseconditions are not likely to exist.

I compared alkanoyloxyacetic acids having 8 to 12 carbon atoms in thealkanoyl group with other alkanoyloxyacetic acids and lauroyloxyaceticacid with a wellknown commercial vapor phase type rust inhibitor,apparently dicyclohexylammonium nitrite, which I shall designateCompound A. I then compared wax-lauroyloxyacetic acid and mineraloil-lauroyloxyacetic acid coated kraft paper with two commercial papersimpregnated with other vapor phase type corrosion inhibitors whichappeared to be the most widely accepted of the inhibitor impregnatedpapers presently on the market. These two commercial papers I shalldesignate additional twenty-four hours.

as Paper X and Paper Y. Paper X apparently was impregnatedwith'dicyclohexylammonium nitrite. Paper Y was apparently impregnatedwith monoethanolamine. Example I I first compared homologs of thealkanoyloxyacetic "acid series having between six and sixteen carbonatoms in the alkanoyl group according to- Procedure I which in outlineis as follows. A short form, four ounce bottle was fitted with aBakelite screw cap in which a small hole was drilled. A glass hook wasinserted in the cap through this hole. A freshly ground, mild steelstrip 2%" x /2" x Vs" with a A" hole drilled through one end was hungfrom the hook. Fiveml. of distilled water and a known quantity of thesubstance to be .tested were put in the bottle. The cap with thesuspended steel coupon was screwed on and the assembly placed Before,reuse in another test, the bottles, caps and hooks were cleaned withchromic acid cleaning solution to insure against carry-over of materialfrom a previous test.

For research projects, little differentiation has been drawn between Aresults wherein no rust is observed on the test coupons and B++ resultswhich describe test coupons containing a maximum of rust covering 0.25%of the total surface area under test. Practically, this is not a sharpdifferentiation, in that inaccuracy of test specimen preparationfrequently leaves minute, sensitive areas and as a result, B++ resultsare frequently obtained with compositions which should give no rust. Itherefore conclude that B++ or A results are substantially equivalentwithin the accuracy of the test.

I then compared the same alkanoyloxyacetic acids in accordance withProcedure II which was the same as Procedure I except that a knownquantity of the. compound to be tested was coated on the inside wall ofthe bottle instead of being admixed with the water so that it would notdissolve in or remain below the water phase.

The results are indicated in-the data given below:

Example I] I next compared lauroyloxyacetic acid with Compound Aaccording to Procedure III which differed from Procedure I in onerespect. The cap, hook, coupon and bottle with a known quantity of testcompound coated on the wall were assembled without water and placed inthe oven at 100 F. for twenty-four hours to allow the inhibitor toprecoat the test strip. The assembly was then removed .from the oven, 5ml..of distilled water added, and the assembly replaced in the oven at100 SP. for an At the end of this'second twenty-four hour period, thecoupons Were'removed and rated as before.

The results are indicated in the data given below:

Lauroyl- Quantity, Grams oxiaccieltic Comment gfi A $2 B++ A B+ B 6%rustB+ B Do.

1 These were long term tests run for 23 days with water present afterthe initial 24-hour period without water.

Example III Blends of lauroyloxyacetic acid and wax and lauroylaceticacid and mineral oil were made and used to coat kraft paper as follows:

Coating 135/1 3d7 F. M. P. fully refined wax +10% lauroyloxyacetic aci .Bleached microcrystalline wax +5% lauroyloxyacetic acid.

Lubedoil viscosity /SSU at 212 F. +10% lauroyloxyaoetic aci These werecompared with two commercial coated papers:

Paper Inhibiting Agent X Dicyclohexylammonium nitrite. YMonoethanolar'oine.

The above papers were cut into strips A x 4" and placed in the testbottles along with the water. Test results are indicated in the datawhich follow:

Paper Result Comment B+, B+- 4% to 8% light rust. B+, B 5% to 12% lightrust. B+, B+ 3% to 6% light rust spots. B+, B+. 2% light rust. B++, B+1% light rust.

I claim:

1. An article of manufacture which is useful in the packaging of metalobjects in order to prevent their corrosion, said article being amaterial to which has been applied a vapor phase corrosion inhibitingcomposition consisting essentially of a non-volatile heavy hydrocarbonvehicle and about 3 per cent to l0per cent by weight based on the totalcomposition of an alkanoyloxyacetic acid having from 8 to 12 carbonatoms in the alkanoyl group. a

2. An article of manufacture which is useful in the packagingof metalobjects in order to prevent their corrosion, said article being amaterial to which has been applied a vapor phase corrosion inhibitingcomposition consisting essentially of a non volatile heavy hydrocarbonvehicle and about 3 per cent to 10 per cent by'weight based on thetotalcomposition of lauroyloxyacetic acid.

3. An article of manufacture which is useful in the packaging of metalobjects inorder to prevent their corro- -sion, said article being papertowhich has been applied tially of petroleum wax and about 3 per cent to10 per cent by weight based on the total composition of lauroyloxyaceticacid.

6. A method of inhibiting corrosion of metal objects in closedcontainers which comprises surrounding said metal objects with anatmosphere containing an alkanoyloxyacetic acid having from 8 to 12carbon atoms in the alkanoyl group in amounts such that at least 0.01pound of alkanoyloxyacetic acid are present for each 100 cubic feet ofair space.

7. A method of inhibiting corrosion of metal objects in closedcontainers which comprises surrounding said metal objects with anatmosphere containing lauroyloxyacetic acid in amounts such that atleast 0.01 pound of lauroyloxyacetic acid are present for each 100 cubicfeet of air space.

8. A method of inhibiting corrosion of metal objects which comprisessurrounding said metal objects with an atmosphere containing analkanoyloxyacetic acid having from 8 to 12 carbon atoms in the alkanoylgroup.

References Cited in the file of this patent UNITED STATES PATENTS2,304,950 Parker Dec. 15, 1942 2,344,404 Giloy Mar. 14, 1944 2,402,825Lovell et al June 25, 1946 2,411,593 Routson Nov. 26, 1946 2,419,327Wachter et a1. Apr. 22, 1947 2,432,839 Wachter et al. Dec. 16, 19472,432,840 Wachter et a1 Dec. 16, 1947 2,464,992 Rehberg et al. Mar. 22,1949 FOREIGN PATENTS 600,328 Great Britain Apr. 6, 1948 596,160 GreatBritain Dec. 30, 1947 OTHER REFERENCES Ind. and Eng. Chem. for December1948, pp. 2338 to 2347 incl. (article by Baker).

1. AN ARTICLE OF MANUFACTURE WHICH IS USEFUL IN THE PACKAGING OF METALOBJECTS IN ORDER TO PREVENT THEIR CORROSION, SAID ARTICLE BEING AMATERIAL TO WHICH HAS BEEN APPLIED A VAPOR PHASE CORROSION INHIBITINGCOMPOSITION CONSISTING ESSENTIALLY OF A NON-VOLATILE HEAVY HYDROCARBONVEHICLE AND ABOUT 3 PER CENT TO 10 PER CENT BY WEIGHT BASED ON THE TOTALCOMPOSITION OF AN ALKANOYLOXYACETIC ACID HAVING FROM 8 TO 12 CARBONATOMS IN THE ALKANOYL GROUP.